Cam-Driven Reading Unit for Shading Correction
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Solution Overview
Problem
Existing image reading apparatuses face challenges in performing accurate shading correction due to variations in light distribution and sensor sensitivity, which can lead to inconsistencies in image quality, especially when the distance between the reading unit and the reference member differs from the distance to the sheet being read.
Innovation Solution
The image reading apparatus incorporates a moving mechanism with a cam-driven system that adjusts the position of the reading unit, allowing it to move between two positions. This mechanism ensures that the distance from the reading unit to the sheet and to the reference member can be precisely adjusted, maintaining consistency in shading correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the reading unit is fixed at a single position, then the structure is simple, but the distance to the sheet and reference member cannot be consistently adjusted for high-accuracy shading correction
Solution Approach 1:
The reading unit is made movable along the optical axis through a cam mechanism driven by a drive source. The cam profile is specifically designed to position the reading unit at two distinct distances: a first distance when reading the sheet and a second distance when reading the reference member for shading correction. This dynamic positioning capability enables high-accuracy shading correction while maintaining a relatively simple overall structure.
2Measurement precision
If the reading unit moves to different positions, then shading correction accuracy improves, but the mechanism complexity increases
Solution Approach 1:
A cam mechanism serves as an intermediary between the drive source and the reading unit. The cam profile acts as a pre-programmed positioning intermediary that automatically establishes the correct reading distances for both sheet reading and shading correction operations. This intermediary mechanism simplifies the overall control system while achieving precise positioning without requiring complex multi-stage actuation systems.
3Adaptability or versatility
If the distance to reference member differs from distance to sheet, then the apparatus can accommodate different components, but shading correction accuracy deteriorates
Solution Approach 1:
The reading unit's position along the optical axis is dynamically adjusted based on the reading task. The cam mechanism enables the reading unit to be positioned at a first distance when reading the sheet and at a second distance when reading the reference member. This dynamic positioning ensures that shading correction is performed at the optimal distance for accuracy while still allowing the system to accommodate different reading scenarios.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables high-accuracy shading correction by maintaining consistent reading distances, thereby improving image quality and reducing variations caused by light distribution and sensor sensitivity issues.
Implementation Method 1
a cam to be rotated by the drive source, and a moving member that abuts against the cam, wherein the moving mechanism is configured to be moved by rotation of the cam
Data Source
AI summary
An image reading apparatus includes a reading unit for reading an image formed on a sheet, a reference member for performing shading correction, and a moving mechanism including a drive source, a cam to be rotated by the drive source, and a moving member that abuts against the cam, wherein, with a conveying direction of the sheet being a first direction, a width direction of the sheet intersecting the first direction being a second direction, and a direction intersecting the first direction and the second direction being a third direction, the moving mechanism is configured to be operable to move the reading unit to a first position and a second position that is different from the first position in position in the third direction.